Abstract
A transglutaminase from human hair follicle-free epidermis was purified to homogeneity using gel filtration and ion exchange chromatography. The enzyme had an apparent Mr = 51,000 +/- 2,000 by sodium dodecyl sulfate electrophoresis, 100,000 +/- 5,000 by discontinuous gel electrophoresis, and 50,000 +/- 2,000 by gel filtration in Bio-Gel A-0.5m agarose. The enzyme cross-linked Factor XIII-free fibrinogen forming gamma dimers and alpha polymers. Either calcium or strontium was necessary for enzyme activity. In the presence of calcium, enzyme activity was increased by heating at 56 degrees or by treating with dimethylsulfoxide. Activation required calcium and occurred in the presence of serine protease inhibitors. The activated and native enzyme had apparently identical mobilities in acrylamide disc electrophoresis and sodium dodecyl sulfate electrophoresis. The Km values for two substrates in the reaction, casein and putrescine, were very similar for the native and the activated enzyme. The activated enzyme had a larger elution volume on Bio-Gel A-0.5m in the presence of calcium than did the native enzyme. The detailed mechanism of activation remains to be determined.
Highlights
A transglutaminase from human hair follicle-free epidermis was purified to homogeneity using gel filtration and ion exchange chromatography
Either calcium or strontium was necessary for enzyme activity
Transglutaminases catalyzing the formation of these t-(y-glutamyl) lysine bonds have been described in liver (l-5), plasma (Factor XIII, fibrin-stabilizing factor) [6], platelets [7], semen (S), guinea pig hair follicles (9, lo), cow snout epidermis [11, 12], and in human epidermis [13]
Summary
A transglutaminase from human hair follicle-free epidermis was purified to homogeneity using gel filtration and ion exchange chromatography. The enzyme had an apparent M, = 51,000 * 2,000 by sodium dodecyl sulfate electrophoresis, 100,000 f 5,000 by discontinuous gel electrophoresis, and 50,000 * 2,000 by gel filtration in Bio-Gel A-0.5m agarose. In the presence of calcium, enzyme activity was increased by heating at 56” or by treating with dimethylsulfoxide. The activated and native enzyme had apparently identical mobilities in acrylamide disc electrophoresis and sodium dodecyl sulfate electrophoresis. The activated enzyme had a larger elution volume on Bio-Gel A-0.5m in the presence of calcium than did the native enzyme. The human epidermal transglutaminase has been purified to homogeneity; some of its characteristics including its activation by dimethylsulfoxide and by heating in the presence of calcium are the subjects of this report
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